Radiographic imaging such as X-ray imaging has been used for a wide variety of applications in various fields. A typical x-ray imaging system includes an x-ray source generating x-ray beams to irradiate a region of interest (ROI), and an x-ray detector detecting the x-ray beams passing through the ROI. To achieve an x-ray image with sufficient information, precise positioning and alignment of the imaging system, especially between the x-ray source and detector, is required. In prior art imaging systems, the x-ray source and detector are physically attached to each other in a rigid and bulky structure such as an enclosed housing. In such imaging systems, the x-ray source and detector are aligned in fixed positions and typically not moveable relative to each other or able to repositioned and/or realigned.
U.S. Pat. No. 6,282,264 describes a method of positioning a digital flat panel in an x-ray imaging system. While the x-ray source and detector are moveable relative to each other, the detector is mechanically connected with an x-ray tube and the alignment of the imager with the x-ray tube is achieved by moving the imager through pre-defined ranges of motion in a known coordinate system physically installed in an examination room.
There are instances that it is necessary to examine or inspect objects such as a suspicious container in a non-destructive way to not trigger, for example, an explosive that might be concealed inside the container. There are also instances that it is impractical to move objects such as a pipeline in use to an examination room for inspection. It is desirable to have a portable x-ray imaging system in these instances so that an x-ray source and a detector can be conveniently positioned, readily moveable and adjusted. Accordingly, there is a need to automatically align an x-ray source and a detector without mechanical linkage for optimum performance of an imaging system.